High power rf relay incorporating heatsink and fluid cooling



y 1966' T. N. TlLMAN ETA]. 3,261,953

HIGH POWER RF RELAY INCORPQRATING HEAT-SINK AND FLUID COOLING Filed Oct. 10, 1963 4 2T i 2 2 f a u x 33 s 2 38j 1 I 39% K \l I 4a a g 4o uh V I 1 41 ll INVENTOR. TED 'HLMAN RlCH H. WINSLOW United States Patent 3,261,953 HIGH POWER RF RELAY INCORPORATING HEAT- SINK AND FLUID COOLING Ted N. Tilman and Richard H. Winslow, San Jose, Calif,

assignors to Jennings Radio Manufacturing Corporation, San Jose, Calif., a corporation of Delaware Filed Oct. 10, 1963, Ser. No. 315,232 Claims. (Cl. 200144) The invention relates to electric switches or relays,

vand particularly to a vacuum switch or relay suitable for radio frequency applications.

One of the objects of the invention is the provision of a rugged vacuum switch or relay capable of handling at least 50 kv. at 4 megacycles.

Another object of the invention is the provision of a rugged vacuum switch incorporating structure facilitating heat-sink cooling of critical components of the switch.

A still further object of the invention is the provision of a vacuum switch constructed in a manner to enable forced air cooling of critical components of the switch.

One of the limiting characteristics of conventional type switches or relays for radio frequency applications is the large inductance generated in the switch due to long conductive paths. It is accordingly a still further object of the present invention to provide a vacuum switch suitable for RF applications of at least 22 megacycles and designed to eliminate excessive inductance in the circuit.

A still further object of the invention is the provision of a switch structure incorporating components capable of fabrication by automatic machinery and which cooperate one with another to permit production line assembly of the switch.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be apparent from the following description and the drawings. It is to be understood however that the invention is not limited to the embodiment described and illustrated in the drawing but may be embodied in various forms within the scope of the appended claims.

Briefly, the switch or relay comprises an evacuated envelope including a dielectric shell hermetically closed at each opposite end by heavy metallic end caps or plates. One of the end plates serves as a fixed contact and terminal for the switch, while the opposite end plate serves as the other terminal and serves also to support the movable contact assembly which is actuated from outside the envelope to make and break a circuit through the switch. The movable contact assembly includes a r resilient metallic contact plate arranged to make and break contact with the fixed contact. The parts are proportioned to provide a predetermined amount of overtravelto insure a requisite amount of contact pressure. Means are also provided in the movable contact assembly functioning to decrease the inductive path over which the current must flow and also cooperating to define a passageway through which a coolant fluid may be forced to cool the conductive path through the switch.

Referring to the drawings:

FIG. 1 is a vertical cross-sectional view through the long axis of the switch, showing the switch in closed position.

FIG. 2 is a fragmentary view in section showing the fixed and movable contacts in open position.

FIG. 3 is a fragmentary plan View illustrating the construction ofthe movable contact plate.

In terms of greater detail, the switch comprises a tubular dielectric envelope portion 2, preferably formed from a high dielectric ceramic, and heavy metallic transversely disposed end plates 3 and 4. End plates 3 and 3,261,953- Patented July 19, 1966 4 are conveniently fabricated from OFHC copper and each is provided with a cylindrically extending peripheral flange 6 to which is hermetically heliarc welded one end of a cylindrical seal ring 7, the other end of which carries a radially extending flange 8 hermetically brazed to the associated metallized end surface 9 of the ceramic envelope portion 2. The configuration of this union is such that differences in thermal expansion and contraction of the metal end plates and the tubular ceramic are accommodated by flexure of the seal ring without imposing a destructive stress on the ceramic.

The inner surface 12 of end plate 3 is milled to provide a large diameter central recess 13 having a bottom surface 14, which is in turn milled to provide a recess 16 of smaller diameter and having a bottom surface '17 for purposes which will hereinafter be explained. As shown in FIGS. 1 and 2 the annular surface area 18 next adjacent the outer periphery of recess 13 constitutes a fixed contact surface for cooperation witha movable contact to make or break a circuit through the switch.

The movable contact assembly is supported on end plate 4 and includes an axially movable resilient metallic contact plate 19, preferably fabricated from beryllium copper sheet and formed with a plurality of circumferentially spaced radially extending slits 21 defining resilient contact fingers 22 adjacent the outer periphery and adapted to resiliently engage contact surface 18. The construction of the movable contact plate is shown best in FIG. 3. The movable contact plate is supported on a thick contact support block 23 fabricated from OFHC copper and having adjacent its outer periphery a cylindrical axially extending flange 24 adapted to abut the underside of movable contact 21 between its outer periphery and the roots of slits 21. A centrally disposed stud 26 on the support block is utilized to secure the movable contact on the support block. As shown in FIG. 1, the central stud is conveniently threaded to receive a nut 27 which clamps the central portion of the movable contact plate on the stud. After tightening the nut is welded to the stud to prevent inadvertent loosening thereof. From the foregoing it will be apparent that upon closing of the switch, the flange 24 functions as a fulcrum for the peripheral contact finger portions of the movable contact plate. The force required to flex the contact finger portions has the effect of decelerating the closing movement of the contact support block thus eliminating all bounce or chatter from the contacts.

The movable contact support block 23 forms a part of the vacuum envelope of the switch and cooperates in this regard with a flexible metallic wall in the form of tubular bellow 29 heliarc welded at one end to a radially extending flange 31 on support block 23. The other end of the bellow is heliarc welded to a radially extending annular flange 32 brazed across the end of a tubular metallic conductor 33, the other end 34 of which is brazed adjacent the inner periphery of the annular end plate 4 as shown.

To actuate the movable'contact the central bore 36 of annular end plate 4 is provided with an apertured bushing or spacer 37 within the inner periphery of which is brazed an elongated tubular bearing sleeve 38. The inner end of the sleeve extends to adjacent the movable contact support block. Both the spacer 37 and bearing sleeve 38 are rigidly brazed to the end plate 4 to provide a vibration-free structure. Slidably disposed within the bearing sleeve 38 is a stem 39, preferably fabricated from tubular OFHC copper and having its inner end secured to the movable contact support block 23 to effect axial movement thereof and of the resilient contact plate. The tubular stem 39 is provided adjacent its inner end with apertures 41 through which air may be forced for passage through the passageway indicated by the arrows for purposes of cooling the support block, bellow and conductor 33.

To insure that entrained foreign particles do not find their way to the bearing surfaces between the tubular stern and the bearing sleeve 33, a shield 42 is provided within the passageway brazed to the outer periphery of the stem adjacent the apertures 41 and interposed therebetween and the associated end of the bearing tube 38. At its outer end the tubular actuator stem is threaded as at 43 to threadably receive a collar 44 secured on the stem in adjusted position by set screws 46, only one of which is shown. The collar 44 is threaded as at 47 for attachment to a source of air under pressure, or other suitable fluid coolant.

From the foregoing it will be seen that the entire movable contact assembly may be fabricated as a separate subassernbly for subsequent mounting within the tubular ceramic 2. The movable contact assembly is inserted into the prepositioned and brazed tubular bearing 33, and the collar 44 turned onto the stem 39 to temporarily retain the movable contact assembly. The end plates 3 and 4 are then chucked in a lathe, which also appropriately supports the tubular ceramic 2 so as to properly position the flanges 6 and 7, and the flanges are then appropriately heliarc welded to make the final hermetic seal of the switch envelope. With the end plates secured in position, the envelope is evacuated through tubulation 48, the stud 26 is permitted to bottom on the surface 17 to form a positive stop for the movable contact after a predetermined amount of resilient overtravel, and the collar 44 is adjusted on the stem 39 until it bottoms on the plate 4. At this point the set screws 46 are tightened to lock the parts in their position as shown in FIG. 1. Ideally the collar 44 and stud 26 abut the respective associated surfaces 4 and 17 simultaneously. In practice appropriate adjustment of the collar will determine whether the stud alone or the collar alone functions as a stop.

We claim:

1. A high power RF relay comprising an hermetically sealed envelope including a tubular dielectric envelope portion, an end plate closing each opposite end of the tubular dielectric envelope portion and constituting a terminal electrode of the relay, one of said end plates having a recessed central face portion and an annular peripheral surface area protruding out beyond said recessed portion within the envelope and all within the same general locus of said one end plate and constituting an annular fixed contact, a movable contact assembly mounted on the other end plate and including a contact support block having a face area adjacent and smaller than the recessed face portion with the annular fixed contact, an axially extending flange adjacent its outer periphery and a resilient metallic contact plate mounted on said face of the contact support block and having a plurality of circumferentially spaced radially extending slits defining resilient contact fingers extending radially outward beyond said axially extending flange for contact with said annular fixed contact, said axially extending flange abutting the underside of said resilient metallic contact plate between its outer periphery and the roots of said slits therein.

2. The combination according to claim 1, in which stop means are provided to limit over-travel of the resilient contact in a closing direction.

3. The combination according to claim 1, in which stop means are provided to limit movement of the movable contact in an opening direction.

4. The combination according to claim 1, in which said movable contact assembly also includes a tubular conductor extending into the envelope and hermetically united at one end to said other end plate, a tubular flexible metallic wall hermetically sealed to the inner end of the tubular conductor said contact support block being hermetically united to the end of the tubular flexible metallic wall.

5. The combination according to claim 1, in which A a passageway is provided to convey a coolant fluid through the movable contact assembly.

6. The combination according to claim 4, in which the contact support block is of relatively thick copper material and constitutes a heat sink for the movable resilient contact.

'7. A high power RF relay comprising an hermetically sealed envelope including a tubular dielectric envelope portion, an end plate closing each opposite end of the tubular dielectric envelope portion and constituting a terminal electrode of the relay, an annular surface area on one of said end plates within the envelope and adjacent its outer periphery and constituting an annular fixed contact, a movable contact assembly mounted on the other end plate and including a resilient metallic contact plate movable into and out of engagement with the annular fixed contact, a tubular conductor extending into the envelope and hermetically united at one end to said other end plate, a tubular flexible metallic wall hermetically ealed to the inner end of the tubular conductor, a contact support block hermetically united to the end of the tubular flexible metallic wall to support the movable re silient contact plate in operative relation to the fixed con tact, a tubular slide bearing mounted on said other end plate radially spaced within the tubular conductor to provide an annular passageway therebetween, a hollow actuator stem slidably journaled within the slide bearing and provided with apertures communicating the interior of the hollow actuator stem with said passageway, and shield means fixed on the exterior of the hollow actuator stem and extending into said passageway to preclude the entry of solid particles of foreign matter between the bearing surfaces on said actuator stem and slide bearing.

8. A high power RF relay comprising an hermetically sealed envelope including a tubular dielectric envelope portion, an end plate closing each opposite end of the tubular dielectric envelope portion and constituting a terminal electrode of the relay, an annular surface area on one of said end plates within the envelope and adjacent its outer periphery and constituting an annular fixed contact, a movable contact assembly mounted on the other end plate and including a resilient metallic contact plate movable into and out of engagement with the annular fixed contact, a tubular conductor extending into the envelope and hermetically united at one end to said other end plate, a tubular flexible metallic wall hermetically sealed to the inner end of the tubular conductor, a contact support block hermetically united to the end of the tubular flexible metallic wall to support the movable resilient contact plate in operative relation to the fixed contact, said movable contact support block being provided with a centrally disposed stud about which the inner periphery of the resilient movable contact plate is secured, and a cylindrical peripheral flange concentrically disposed about the central stud and abutting the movable contact plate adjacent its outer periphery.

9. The combination according to claim 8, in which the movable contact plate is provided with a multiplicity of radially extending slits adjacent its outer periphery, and said support block flange abuts the movable contact plate between the outer periphery thereof and the root of said slits so as to provide a multiplicity of flexible contact finger portions fulcrumed on said support block flange.

10. A high power RF relay comprising an hermetically sealed envelope including a tubular dielectric envelope portion, an end plate closing each opposite end of the tubular dielectric envelope portion and constituting a terminal electrode of the relay, an annular surface area on one of said end plates within the envelope and adjacent its outer periphery and constituting an annular fixed contact, a movable contact assembly mounted on the other end plate and including a resilient metallic contact plate moveable into and out of engagement with the annular fixed contact, a tubular conductor extending into the envelope and hermetically united at one end to said other end plate, a tubular flexible metallic Wall hermetically sealed to the inner end of the tubular conductor, a contact support block hermetically united to the end of the predetermined amount of resilient over-travel by said movable resilient contact plate.

References Cited by the Examiner UNITED STATES PATENTS 2,972,032 2/1961 Persson 200-144 2,993,971 7/1961 Pfianz 200-166 3,017,479 1/1962 Jennings 200-144 3,082,307 3/1963 Greenwood et al. 200-144 10 3,196,236 7/1965 Jennings 200-144 ROBERT S. MACON, Acting Primary Examiner.

KATHLEEN H. CLAFFY, Examiner.

P. E. CRAWFORD, Assistant Examiner. 

1. A HIGH POWER RF RELAY COMPRISING AN HERMETICALLY SEALED ENVELOPE INCLUDING A TUBULAR DIELECTRIC ENVELOPE PORTION, AN END PLATE CLOSING EACH OPPOSITE END OF THE TUBULAR DIELECTRIC ENVELOPE PORTION AND CONSTITUTING A TERMINAL ELECTRODE OF THE RELAY, ONE OF SAID END PLATES HAVING A RECESSED CENTRAL FACE PORTION AND AN ANNULAR PERIPHERAL SURFACE AREA PROTRUDING OUT BEYOND SAID RECESSED PORTION WITHIN THE ENVELOPE AND ALL WITHIN THE SAME GENERAL LOCUS OF SAID ONE END PLATE AND CONSTITUTING AN ANNULAR FIXED CONTACT, A MOVABLE CONTACT ASSEMBLY MOUNTED ON THE OTHER END PLATE AND INCLUDING A CONTACT SUPPORT BLOCK HAVING A FACE AREA ADJACENT AND SMALLER THAN THE RECESSED FACE PORTION WITH THE ANNULAR FIXED CONTACT, AN AXIALLY EXTENDING FLANGE ADJACENT ITS OUTER PERIPHERY AND A RESILIENT METALLIC CONTACT PLATE MOUNTED ON SAID FACE OF THE CONTACT SUPPORT BLOCK AND HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED RADIALLY EXTENDING SLITS DEFINING RESILIENT CONTACT FINGERS EXTENDING RADIALLY OUTWARD BEYOND SAID AXIALLY EXTENDING FLANGE FOR CONTACT WITH SAID ANNULAR FIXED CONTACT, SAID AXIALLY EXTENDING FLANGE ABUTTING THE UNDERSIDE OF SAID RESILIENT METALLIC CONTACT PLATE BETWEEN ITS OUTER PERIPHERY AND THE ROOTS OF SAID SLITS THEREIN. 